Digital communication interfaces have become widespread with modern technology's emphasis on rapid transfer and communication of digital data for an ever-increasing amount of important functions, including data storage, output transmission, and device control. These interfaces include standard communication specifications such as Universal Serial Bus (USB), Serial Advanced Technology Attachment (SATA), Firewire, etc. These interfaces are used in a number of applications for computers and other electronic devices.
USB, for example, is a commonly-used interface standard that allows data communication between a host and one or more peripheral devices. The host controller communicates with the peripheral devices using one or more USB ports of the host connected to the peripherals.
Some functions of USB-compatible devices may vary or be altered based on whether the device is connected to a host computer or whether the device has a cable currently connected to one of its ports. For example, blood glucose measurements are often performed by users for monitoring the health status of themselves or others with respect to blood glucose level. These measurements are commonly taken utilizing a blood glucose meter device that can be connected to a computer with which the meter can communicate data, where the connection is by a USB cable. In some such devices, measured readings can be sent to the computer and/or configuration information can be received at the device from the computer over the USB cable. These devices are intended to be disconnected from the computer and the USB cable before they are used to take blood glucose measurements.
One problem with such blood glucose meter devices is that when blood glucose measurements are taken with a USB cable still connected to the device, the measurements may be inaccurate due to the electrical and/or magnetic effects of the cable on the measurements. These effects are present whether a computer is or is not connected to the opposite end of the cable. Since many users do not know, or forget, to disconnect the cable before taking measurements with the device, a significant number of measurements taken by users may therefore be inaccurate. Such inaccuracies in some cases may be quite harmful to the patient if, for example, a serious or life-threatening health condition is not detected due to inaccurate measurements, and/or a doctor cannot interpret accurate data from a patient. Other types of devices may similarly be intended to be disconnected from the interface cable and may have undesired performance or functions when a cable remains connected during their use.
There are some existing approaches to detecting a USB cable connection to a blood glucose meter device. In one approach, the device tries to detect the presence of a connected USB host, such as the computer, via the presence of pull-down resistors on the D+/D− signals of the USB interface. In another approach, detection of the USB cable shield terminal connection to ground is attempted in the computer or charger device in the peripheral device. However, neither the pull-down resistor connection nor shield connection to ground is mandated when the voltage on the USB bus is missing and thus detection of cable and computer is unreliable. These methods also fail to detect a cable that is connected to the meter device while not being connected to a computer or other device on the other end of the cable.
These and other limitations of the prior art will become apparent to those of skill in the art upon a reading of the following descriptions and a study of the several figures of the drawing.